SC.3.L.15.1 Classification

SC.3.L.15.1 Classify animals into major groups (mammals, birds, reptiles, amphibians, fish, vertebrates and invertebrates, those having live births and those which lay eggs) according to their physical characteristics and behaviors.

What is Classification?

Science is knowing and understanding the world around us. Scientists study plants and animals. To describe plants and animals in the world around us, scientists have developed ways to identify groups of animals based on similarities and differences. This system of grouping is called classification.

We already used the first classification: plants and animals. Now we will look at the ways that scientists describe animals to classify them into groups. The first major description is animals with a backbone (vertebrates) and animals without a backbone (invertebrates). The diagram at the top left shows these two categories at the top.

Next, scientists group vertebrates according to whether they are warm blooded (able to control their own body temperatures) or cold blooded (unable to control their own body temperature. Mammals and birds are the two warm blooded categories. Reptiles, amphibians, and fish are cold blooded. 

As you can see from the diagram, there are many categories of invertebrates. Some of those animals might be familiar, like clams and oysters (mollusks) and starfish (echinoderms). In elementary science, we focus on grouping arthropods.

Arthropods are invertebrates with legs. This includes insects and spiders. It also includes crustacea: shrimp, lobsters, and crabs are all crustacea. Millipedes and centipedes are classified as myriapods. In addition to having many legs, another common characteristic of arthropods is an exoskeleton, or shell.